157 lines
3.7 KiB
C
157 lines
3.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Functions related to softirq rq completions
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/bio.h>
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#include <linux/blkdev.h>
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#include <linux/interrupt.h>
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#include <linux/cpu.h>
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#include <linux/sched.h>
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#include <linux/sched/topology.h>
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#include "blk.h"
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static DEFINE_PER_CPU(struct list_head, blk_cpu_done);
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/*
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* Softirq action handler - move entries to local list and loop over them
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* while passing them to the queue registered handler.
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*/
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static __latent_entropy void blk_done_softirq(struct softirq_action *h)
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{
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struct list_head *cpu_list, local_list;
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local_irq_disable();
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cpu_list = this_cpu_ptr(&blk_cpu_done);
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list_replace_init(cpu_list, &local_list);
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local_irq_enable();
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while (!list_empty(&local_list)) {
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struct request *rq;
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rq = list_entry(local_list.next, struct request, ipi_list);
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list_del_init(&rq->ipi_list);
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rq->q->mq_ops->complete(rq);
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}
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}
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#ifdef CONFIG_SMP
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static void trigger_softirq(void *data)
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{
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struct request *rq = data;
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struct list_head *list;
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list = this_cpu_ptr(&blk_cpu_done);
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list_add_tail(&rq->ipi_list, list);
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if (list->next == &rq->ipi_list)
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raise_softirq_irqoff(BLOCK_SOFTIRQ);
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}
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/*
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* Setup and invoke a run of 'trigger_softirq' on the given cpu.
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*/
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static int raise_blk_irq(int cpu, struct request *rq)
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{
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if (cpu_online(cpu)) {
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call_single_data_t *data = &rq->csd;
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data->func = trigger_softirq;
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data->info = rq;
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data->flags = 0;
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smp_call_function_single_async(cpu, data);
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return 0;
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}
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return 1;
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}
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#else /* CONFIG_SMP */
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static int raise_blk_irq(int cpu, struct request *rq)
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{
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return 1;
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}
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#endif
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static int blk_softirq_cpu_dead(unsigned int cpu)
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{
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/*
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* If a CPU goes away, splice its entries to the current CPU
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* and trigger a run of the softirq
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*/
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local_irq_disable();
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list_splice_init(&per_cpu(blk_cpu_done, cpu),
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this_cpu_ptr(&blk_cpu_done));
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raise_softirq_irqoff(BLOCK_SOFTIRQ);
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local_irq_enable();
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return 0;
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}
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void __blk_complete_request(struct request *req)
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{
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struct request_queue *q = req->q;
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int cpu, ccpu = req->mq_ctx->cpu;
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unsigned long flags;
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bool shared = false;
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BUG_ON(!q->mq_ops->complete);
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local_irq_save(flags);
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cpu = smp_processor_id();
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/*
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* Select completion CPU
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*/
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if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) && ccpu != -1) {
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if (!test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags))
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shared = cpus_share_cache(cpu, ccpu);
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} else
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ccpu = cpu;
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/*
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* If current CPU and requested CPU share a cache, run the softirq on
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* the current CPU. One might concern this is just like
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* QUEUE_FLAG_SAME_FORCE, but actually not. blk_complete_request() is
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* running in interrupt handler, and currently I/O controller doesn't
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* support multiple interrupts, so current CPU is unique actually. This
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* avoids IPI sending from current CPU to the first CPU of a group.
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*/
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if (ccpu == cpu || shared) {
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struct list_head *list;
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do_local:
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list = this_cpu_ptr(&blk_cpu_done);
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list_add_tail(&req->ipi_list, list);
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/*
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* if the list only contains our just added request,
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* signal a raise of the softirq. If there are already
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* entries there, someone already raised the irq but it
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* hasn't run yet.
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*/
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if (list->next == &req->ipi_list)
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raise_softirq_irqoff(BLOCK_SOFTIRQ);
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} else if (raise_blk_irq(ccpu, req))
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goto do_local;
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local_irq_restore(flags);
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}
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static __init int blk_softirq_init(void)
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{
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int i;
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for_each_possible_cpu(i)
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INIT_LIST_HEAD(&per_cpu(blk_cpu_done, i));
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open_softirq(BLOCK_SOFTIRQ, blk_done_softirq);
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cpuhp_setup_state_nocalls(CPUHP_BLOCK_SOFTIRQ_DEAD,
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"block/softirq:dead", NULL,
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blk_softirq_cpu_dead);
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return 0;
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}
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subsys_initcall(blk_softirq_init);
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